Apparatus for the manufacture of tapered conductors



G. F. LAING Aug. 19, 1952 APPARATUS FOR THE MANUFACTURE OF TAPEREDCONDUCTORS Filed March 29, 1945 4 2 SHEETS-SHEET 1 R m m w.

GORDON F. LAING Y w A G. F. LAING Aug. 19, 1952 2 SHEETSSHEET 2 FiledMarch 29, 1945 Y. m WW 2 A L mF M m N Q O D D. O 3 s w Y/ B B O\ \NRwQ mQ on Patented Aug. 19, 1952 APPARATUS FIOR THE .MANUF-ACTURE OF 'TAPERED'CONDUCTORS Gordon F. Laing, Delavan, Wis., assignor to The George W.Borg Corporation, Chicago, 111., a corporation of Delaware ApplicationMarch 29, 194.5,SerialNo. 585,475

3 Claims. (01. 204-206) The present invention relates in general tomethods and apparatus for the manufacture of .tapered conductors, suchas are suitable for use in .the manufacture .of none-linear rheostatsand .potentiometers, an the object of the invention isto provide new.and improved methods .andapparatus of this character.

The invention maybe considered as an improvement-on the inventiondisclosed in the pending application of Thomas B. Gibbs et 8.1., SerialNo. 525,764 filed March 9, 1944 .(now Patent 2,605,218) which disclosesa method and apparatus for making tapered conductors from conductors orwires of nm'iorm .cross section by drawing such wirespthrough .anelectrolytic bath, in .w-hichthey are subjected to anodicreduction. Thetaper. isproduced by progressively decreasing the speed at which thewires are drawn through the bath, thereby progressively increasing thetime in .the bath and the amount of metal removed from the wires.

A -feature of thepresentinvention is the use of alternating current in.the electrolytic bath rather than direct current, whichmakes possible amore compact and efficient arrangement of the electrolytic cell system.

,A furtherfeature of the invention is the use of alternating .current ofrelatively high frequency,.onthe order of 10.00cycles per. second, orhigher, which reduces the evolution .of.gas in the 'electrolyticcellsand increases the rate of anodic reduction.

The foregoing and other features will .be ,de-

.scribed more injdetail hereinafter with reference e t r l ind ca spartof .atebla benc v-or..[ot r support on which the apparatus is mounted.

The supportlO' has a rectangularjopenins.therematerial .or .sh0uld1have.a lining of acid-proof material.

"The; tank is. dividedinto. two sections; I and II,

Fig. e. .by eniimpervious :and mwmnducfilng .partition. t9. v I

Twobars 1'4 and t5 are provided for supporting the;electrolyt ic c ellsabovethe tank. he; one

'end'the 'barsrest on" the "flange 13 of (the tank a d at t e ther end.t e rest on th ros ba l5 which is secured to the sides of the tank, asjindicated in Fig. 1. These bars may be made of suitableacid-proofmaterial such as polystyrene.

There must be at least two'electrolytic cells, and forefiicientoperation there should be a considerable number of them. The drawingsv*sl rowfourteen cells, indicated by reference char- .acte'r zl to 34,inclusive. These cells and the two. headers ll. and [8 are preferablymade'from strips. of polystyrene secured together by means of a cementmade by dissolving polystyrene in a "suitable organic solvent.

.Theelectrolytic cell 22 comprises'a bottom strip' 3l, which rests onthe bars l4 and 1 I5, the side strips '35 and .36, and. the short endstrip '38. These strips are cemented'together as 'previously .mentionedand form a relatively long I and narrow cell which is open at one endand is closed at the other end by the end strip-3'8. The sidewalls 35"and 36 have slots as indicated at '44, "Fig. .3, and there is apartition 39 near the closed end o f'the cell. This partition is lower'than the cell walls but is somewhat higher than the bottoms of theslots 44. Between the partition andflthe end wall 3 8 there is anopening AI leading to the pipe-or tube 42. which is cement ed to thebottom strip 31. The reference characters!) indicates an electrode whichis-preferably a stripof platinum resting on'the bottom of the cell. Atthe left hand end the electrode is held down-by the partition"39 asshown in Fig. 3, and-at the right hand end it isbent down aroundtheendof the bottom stripj-l.

'The'cells 23t 33, inclusive, are-the same as the cell'22 "which hasbeendescribed. The'two end cells-2| and 34 are the same also, exceptthat the' side -walls =-"4-5 and 48 are made-somewhat "longer so as toform the-end walls of theheaders l1 and 1.1

The cells are'arranged on the bars l4 and [5 as shown in Fig. 1, withthe odd numbered cells 22', 2. .e h vin their op nds a ne si of theassembly while the even numberedcells :22 .24. s t h thei open dsv on hoth side. The cells arespaced apart by the end walls such as "38,whichshould becemented to the side walls of the'adiacent cells aftertheyhave been properly lined up. Inthis way the cells are firmlysecuredtogether.

Thehea'der' IT- has the bottom strip 41 and the sidewall strip 4'6and-the ends are closed bythe extended sidewalls 45- and'48 of the cells34-and -21. l -b tt strip s shallow notches at [the points where theelectrodes suchnas v4|] leave the associated cells,- to avoid leaving aspace between the'edge of the strip and the .'ends.0f the I cells. Theparts being well cementedtpgether i easie is viQ l l lw ich spans the.row .of .cells and opens intotheeven numbered cells.

wall 49 of the header.

The header It includes the bottom strip 49 and the side strip or wall 50and is similar to header IT. The header 18, however, opens into the oddnumbered cells.

After the cells and headers are assembled as described the joints may bepainted with the.-

polystyrene cement to insure that no leaks are present.

The electrodes such as 40 which are associated? with the even numberedcells are all connected to the bus bar 52, while the electrodesassociated with the odd numbered cells are connected to' .knownconstruction and need not be described in detail. The pump 53 is locatedin the well [2, section II, and. delivers electrolyte from section II ofthe tank to the vertical pipe 55, whence it flows to the header l8 byway of the horizontal pipe 55, the hose '1, theelbow 58, and thechanneled block 60, which is cemented to the bottom Ifhe othercirculating system includes the motor 56 and a pump similar to pump 53.The pump associated with motor 54'. is located in the Well l2,sectio'nI, and delivers electrolyte fromsection .I of the tank to theverticalpipe 6 I, whence it flows to the header H through horizontalpipe 52, hose 83, elbow 58', and the channeled block 60'.

The volume of electrolyte delivered to the headers is controlled bymeans of the valves 64 and 67. The stem of valve 54 is threaded into 7 arectangular plate 66 which is supported on the or the other by meansof ascrew driver to raise or lower the V-shaped valve head and thus regulatethe effective area of the opening in the bottom l! of the header throughWhichthe electrolyte flows from the channel in the block 60. A locknut65 is provided by means of which the valve can be secured in adjustedposition. The valve 61 is similar to valve 64 and regulates th flow ofelectrolyte into the header [8. 1

The composition of the electrolyte may vary somewhat depending on thekind of wire to be processed. For the manufacture of tapered conductorsfrom Nichrome or similar resistance wire a mixture of ortho-phosphoricacid and sulphuric acid has been found to give good results.

composition, for example, may be as follows:

Parts .In the above formula, the proportions given are by volume. Thesulphuric acid is concen- .maintained constant at a fairly high value,50

degrees C., for example. Although not shown in the drawings, it will beunderstood that suitable heating and temperature control apparatus willbe provided. Apparatus such as disclosed in the Gibbs et al. applicationpreviously referred to may be used.

The cell 69 is a washing cell and is supplied with water through asuitable hose connection 68. The water fills the cell 69 to the level of13 and I l. circuit. The primary winding of the transformer T8 isconnected to the single phase A. C. genera- 4 the end wall llover whichit. overflows into the outer cell 18 which is drained by the hose 19.The walls of the cells 'EQand '18 are slotted like the walls of theelectrolytic cells 2 I, 22, etc.

The first four electrolytic cells 2| to 24 are shown diagrammatically inFig. 4, with the bus bars 5| and 52. These-bus bars are connected to thesecondary winding of the constant current transformer Ill by means ofthe conductors An animeter H is included in the tor 15 by way of theauto-transformer 12. The generator E5 is driven by the motor it which issupplied with commercial current through the switch Si.

The motor generator set itis employed in order to convert the commercialalternating current having a frequency of 60 cycles per second intoalternating current of .higherfrequency, 3000 cycles per second, forexample. Otherarrangements for supplying high frequency alter- I natingcurrent could be used.

The wires 8|, 82, 83 and 84 from which tapered conductors are to' bemade are carried on the spools B5, 86, $7 and 88, respectively, whichare supported for rotation in any suitable manner. Braking devices (notshown) may be provided to prevent free rotation of the spools.

The wires 8i-84 are drawn through the electrolytic cells by winding themon the four take-up spools 855-92. 7 These spools are clamped againstthefiange 93 on shaft 94 by means of the wing nut 95.

Two notched guide rods are indicated at 96 and 97. It will be understoodthat in practice the spools $5'88 are located at least several feet awayfrom the guide rod 99, so that there will be no danger of the wiresslipping out of the notches in the guide rod as they unwind from thespools. The same is true as regards the relation between the spools89-92 and the guide rod 91, although the spacing here is desirablemainly in order to afford the necessary room for a suitable devicelnotshown) for causing each wire to be wound up on its asociated spool in asingle evenly applied layer.

The shaft 94 is driven by the motor 98 through the medium of a variablespeed mechanism 99. A variable speed mechanism such as is disclosed inthe Gibbs et a1. application previously referred to may be used. Anothervariable speed mechanism which is suitable for the purpose is disclosedin the application of Gordon F. Laing, Serial No. 547,041, filed July28, 1944 (now Patent 2,422,306). v The operation of the apparatus in themanufacture of tapered conductors may now be explained, it being assumedfor this purpose that the apparatus is installed and connected up asshown diagrammatically in Fig. 4.

The Well I2 of the tank having been filled with electrolyte, the switchS3 may be closed to start the motors 54 and 54' which drive the pump 53and the corresponding pump in the other section of the tank. Theoperation of the pumps transfers electrolyte from the Well to theheaders l1 and 18 from which it flows into the electrolytic cells,header I! supplying electrolyte to the even numbered cells 22, 24, etc.and header I8 supplying electrolyte to the odd numbered cells 2|,

, 23, etc.

anon-24 5, tio'rr 39.1.v As the: electrolyte. continues. to. enter.thecell it. begins; to..overfiow= over; the partition and' iszreturnedto'the tank by way of; the drainage :opening ('41. and the tube; 42..-Thus a definite current. of: electrolyte is. established, flowing,

lengthwise of thecell...

The action at:the othercells=is thesame'as described, the: electrolyte.entering; each cell: at its open: end. overflowing the partitionat--,the opvpositeuend, .andd'raim'ng. backrto-thetank byway:

offthe: associated drainagegopening. The valves. 64' and? 61' shouldcbeadjusted; to supply an -adequatevolumexotelectrolytetdthe headers l1 andI8, suflicientto maintain a vigorous flow-through the; cells. In: this:connectionit will be understood; that the pumps have some excesscapacity andzthat the :valves: are adjusted to limit the volume: ofelectrolyte delivered to theheaders to the desiredvalue.

It will. be. notedthat the-drainagdtuberlz for. celL 2 2:. andthe tubesrwhich. drain the: other; even numbered cells all. empty into section I,of the tank; fromxwhichelectrolyte is. pumped to the header IT tosupply. these even numbered cells. The drainage tubesirom'the-oddznumberedcells, onthe other handempty into section II ofthetank, from whichelectrolyte is. pumped toheader l8- for the oddnumberedcells. .Theodd and even numbered: cells-are thus suppliedbyseparate cinculating systems which are electrically, insulated from eachother by thepartition. IS in theLtank'.

The'wash water may now beturnedon and enters-the" washing cell 59 by wayof the. hose connection 68, filling the cell and overfiowingover the endwall 1'! of the washing cell into the outer cell-"I8 whence it isdrainedoff. through the hose connection I9.

Dueto the slbts-Minthewalls of the electrolytic cells, a certain amountof leakage occurs. The electrolyte which leaks through the slots runsdown the outside of thecell walls, which are spacedapart far enough-forthis action to take place, and drips intothe tank. There is alsoaleakage of water throughthe slots in the walls of the-washing cell 69;The leaka'ge water collects in the 'outer cell 'l8-in which the-waterlevel is lowerthan the bottoms of the slots due to the location of thedrainage opening near the bottom; Accordingly, there no leakage throughthe slots inthe walls of cell 18: I v

It-may'be assumed now that the four spools of wire 85-88 have beenplaced on theirsupports as indicated-and that the four take-up spools89-92 have. been assembled on shaft 94. The wires 817-434 are pulled'off from their respective spools one at a; time and" are" passed underthe guide rod 96, over-the'electrolytic cell system, under theguiderodfll; and arefinally attached'to the-takeup spools; notchesbeingprovided in the flanges ofithe takeup spools for this purpose. The wiresare then adjustedin'the notches of the guide rods and in the slots ofthe electrolytic cells and washer cells and the spools 85-88 arerotated'backwards if necessary until the wires become taut. It will beunderstood that the lower sides of the guide rods 96 and 91 shouldbe atthe same level or slightly lower" than thebottoms of the slots in thecell walls: so that; as the -wires are drawn through there will be notendencyv for. them to rise in the. cells.

The operator may now close the switch SI to start the motor generatorset l6 l5. The'generator-IS'; having-attainedits running speed, deliversalternating current to the primary winding of the transformer 10,the'secondary winding of which delivers alternating :current totheqelectrolytic cellsystem. The amount of currentflowingin.the.;secondary, circuit is indicated by the. am--. meter H: and-Jit maybeassumed that thepauto -a transformer-12' has been adjusted so that thecurrentrhasthe proper value. The-current should be as highaspossible'consistent with. the. carrying capacity of the wires. In themanufacture of ta.- pered. conductors. having a. largerv diameter ofabout 5'to;8 mils and'a smaller diameter. of about l mil .orimore; withthe apparatus: described about 32amperes per wire may be used.Thehighzcurrrent valueis desirable in order. to-givethe: taperedwiresasmoothsurface.

The anodic reduction of the wires takes place in the odd and evennumbered. cellsalternatel'ya Duringthe half cycles in which the busbar5l is positive. current-flows over a circuit which may be tracedfrom'bus bar 52, platinum electrodes in the even numbered cells,electrolyte in the even numbered cells,- wires- 8.|'--8, electrolyteinthe odd numbered cells, platinum electrodes in the odd numbered cells,and the bus bar 51, and anodic reduction takes place in the even numbered cells, where the wires are positive with respect tothe electrodes;During the intervening'halr cycles the circuit isthesame-butthe-direction of current flow is reversed-and anodic' reduction of thewires takesplace in the odd numbered cells.

The evolution of gas is lessthan in an apparatus using direct current.The gases'produced in each type of apparatus are' hydrogen and oxygen.Both hydrogen and oxygen are produced by electrolysis ofthe water intheelectrolyte. The gases are liberated asatomic hydrogen H and'atomicoxygen 0 and can combine' toform water H2O if given an opportunity todo; so, being otherwise separately converted to molecular hydrogenI-Ia'and molecular oxygen Ozwhich are given ofi as bubbles-of gas.

The reduction in gassing in thepresent ap paratus, using alternatingcurrent isbelieved'to be'due to the fact thatwiththis type ofapparatusithe gases have a greater opportunity to combine to form water.In the direct current apparatus the hydrogen and oxygen produced byelectrolysis are liberatedat difierent' electrodes, hydrogen beingliberated at the cathode and oxygen at the anode (the wires), and haveno chanceat all torecombine; The hydrogen pro-- duced byanodicreductionof the wires is also liberated at the cathode. In thealternating current apparatus, on' the other hand; the hydrogen andoxygen produced-by electrolysis and the hydrogen produced-by anodicreduction are liberated at the same electrodes, since in each cell thewires function alternately as cathode and anode, and the gases have anopportunity to recombine. The. formation of water in this Way results insome reduction in gassing even if low frequency 60 cycle alternatingcurrent is used; The efiect is increased with an increase in thefrequency and itis advantageous, there fore; to use a fairly highfrequency. Frequencies on-the orderof 1000 to 5000 cycles-per secondmaybe-used with good results.

The reduction-in the amount ofgassin has the special advantage. that thetendency. to polarizationof the wires is reduced and the ree duction ofthe wires is correspondingly Haccelerated.

At the same time that the switch SI is closed tostart the anodicreduction process the switch S2 maybe close.d'also,.to start the motor98.

or conductors having the length and taper .re-

quired. vThese instructions may, for example, specify a wire having adefinite number of sec-, tions, the length and pulling speed of whichare designated. The length of the sections maybe given in terms ofrotations of shaft 94qwhile the pulling speeds may be given as differentsettings of the variable speed mechanism. These settings are calculatedin advance in accordance with the taper required.

Before starting the operation, therefore, the operator will adjustthe'knob I of the variable speed mechanism to the correct setting forthe first section. Then, as the wires are pulled through, the operatorcounts the rotations of shaft to keep track of the sections and as eachsection emerges from the electrolytic cell system she will adjust theknob Hill to the setting which is specified for the next section. Arotation counter may be used in connection with shaft 94, if desired,and will be of assistance to the operator.

When the end sections have been pulled through, and a few feet of wirein addition, the operator will stop the operation by opening theswitches SI and S2. The switch S3 may be left closed assuming that moretapered wires are to be made. The wires on the take-up spools are nowcutoff one at a time where they emerge from the electrolytic cell system,the winding of these wires on the spools is completed by hand, and thespools are removed from the shaft 94. Four. tapered wires have now beencompleted.

To make four more tapered wires, the operator will place four emptytake-up spools on shaft 94, and reset the variable speed mechanism. Thewires 3|-84 are then cut ofi just to the left of the point where theyenter the electrolytic cell system and the sections of wire in' theelectrolytic cell system are lifted out and'discarded. The ends of thewires on the spools 85-438 are then passed beneath the guide rods andare attached to the take-up spools as before. These matters having beenattended to and the wires having been adjusted in the grooves of theguide rods and in the slots of the cell walls, the switches SI and S2may be closed again, whereupon the described tapering operations arerepeated. 7

The apparatus may also be used for manufacturing very fine wire ofuniform diameter, starting with a wire having a diameter of 4 or 5 milssuch as can conveniently be produced by drawing and reducing it to thedesired smaller diameter by pulling it through the electrolytic cellsystem. The pulling speed is determined in accordance with the reductionrequired and is maintained constant throughout the operation.

The invention having been described, that which is believed to be newand for which the protection of Letters Patent is desired will bepointed out in the appended claims.

Iclairm:

1. Apparatus for processing wire by anodic reduction, comprising twogroups of electrolytic 8 cells, said cells being arranged in a row. withthe cellsof one group alternating withthe cells ofthe other group, meansfor drawing aiwire through said cellsptwo independent circulating.systems for circulating electrolyte through said two groups of cells,respectively, saidisystems including parts made of insulating materialfor insulating the electrolyte in one system from the electrolyte in theothersystem, an electrode ineach cell, a source of alternating current,and conductors connecting one terminal ofsaid source to the electrodesin one group of cells and the other terminal of said sourceto theelectrodes in the other groupv of cells.

-2. An electrolytic cell "system for the anodic reduction of wires,comprising a plurality of electrolytic cells spaced apart in a row, aheader extending parallel to said rowon one side thereof andcommunicating with the odd numbered cells, a header extending parallel.to said row on the oppositeside thereof and communicating with the evennumbered cells, two electrolyte storage reservoirs, discharge outletsfor the odd numbered cells emptying into the first of said reservoirs,discharge outlets for the even numbered cells emptying into the secondof said reservoirs, two pumps for transferring electrolyte from .thefirst and second reservoirs to the first and second headers,respectively, means for drawing wires through said cells, a source ofal-, ternating current, electrodes in the odd numbered cells connectedin parallel to one terminal of said source, and electrodes in the evennumbered cells connected in parallel to the other terminal of saidsource.

3. An electrolytic cell system for the anodic reduction of wires,comprising a plurality of electrolytic cells spaced apart in a row, aheader extending parallel to said row on one side thereofandcommunicating with the odd numbered cells, a header extendingparallel to said row onthe opposite side thereof and communicating withthe evennumbered' cells, discharge outlets for the 'odd numberedcells,discharge outlets for the even numbered cells, the discharge outlet for,each cellbeing located at the end op: posite the header with which thecell communi cates, a circulating system for collecting electrolyte fromthe discharge outlets for the odd numbered cells and transferring it tosaid first header, a circulating system for collecting electrolyte fromthe discharge outlets for the even numbered cells and transferring it tosaid second header, means for drawing wires. through said cells a sourceof alternating current, cathodes in the odd-numbered cells connected inparallel to one terminal of saidsource, cathodes in the even-numberedcells connectedin parallel to the other terminal of said source, andparts in said circulating systems made of insulating material to preventcurrent fiow from one group of cathodes to the other group by way of theelectrolyte in said headers. 7 V

GORDON F. LAING.

REFERENCES CITED The following references are 'of record in the file ofthis patent:

(Other references on following page) 9 10 UNITED STATES PATENTS FOREIGNPATENTS Number Country Date Number Name Date 4,120 Great Britain of 18971,607,582 Walker Nov. 16, 1926 428,488 Great Brltam May 14, 19351,614,562 Lalse Jan. 18, 1927 5 467,024 Great Brltam June 9, 19371,721,414 Robe July 16, 1929 683 169 Ge 0 t 31 1939 1,959,531 Hickman eta1 May 22, 1934 many 2,093,238 Domm Sept. 14, 1937 OTHER REFERENCES2,374,449 Mulcahy Apr. 24, 1945 Journal of the ElectrodepositorsTechnical 10 Society, vol. 4 (1928-1929), pages 137 thru 139.

1. APPARATUS FOR PROCESSING WIRE BY ANODIC REDUCTION, COMPRISING TWOGROUPS OF ELECTROLYTIC CELLS, SAID CELLS BEING ARRANGED IN A ROW WITHTHE CELLS OF ONE GROUP ALTERNATING WITH THE CELLS OF THE OTHER GROUP,MEANS FOR DRAWING A WIRE THROUGH SAID CELLS, TWO INDEPENDENT CIRCULATINGSYSTEMS FOR CIRCULATING ELECTROLYTE THROUGH SAID TWO GROUPS OF CELLS,RESPECTIVELY, SAID SYSTEMS INCLUDING PARTS MADE OF INSULATING MATERIALFOR INSULATING THE ELECTROLYTE IN ONE SYSTEM FROM THE ELECTROLYTE IN THEOTHER SYSTEM, AN ELECTRODE IN EACH CELL, A SOURCE OF ALTERNATINGCURRENT, AND CONDUCTORS CONNECTING ONE TERMINAL OF SAID SOURCE TO THEELECTRODES IN ONE GROUP OF CELLS AND THE OTHER TERMINAL OF SAID SOURCETO THE ELECTRODES IN THE OTHER GROUP OF CELLS.